The present invention relates to a vaccine containing antigens from parasitic organisms which cause ringworm, to methods of manufacturing such a vaccine and to methods of treating patients with such vaccine.
Humans and, other mammals, including many types of domesticated animals from dairy cattle to the family cat, are plagued by ringworm (dermatomycosis) which is caused by infection by one or more of a number of parasitic fungi, generally called xe2x80x9cdermatophytesxe2x80x9d (i.e., organisms which upon infection cause ringworm). Dermatophytes include without limitation the species listed in Table I.
Extensive additional information relating to dermatophytes and dermatophyte mycology can be found in xe2x80x9cThe Medical Mycology Handbookxe2x80x9d by Campbell and Stewart (John Wiley and Sons, 1980) (hereinafter the xe2x80x9cCampbell/Stewart Handbookxe2x80x9d), which is incorporated herein by reference as if fully set forth.
Ringworm usually manifests itself as a series of rapidly expanding, irritating lesions which can occur in any area of the skin. Dermatophytes attack chiefly keratinized tissues, particularly the stratum corneum and hair fibers resulting in autolysis of the fiber structure, breaking off of the hair and alopecia. Exudation from invaded epithelial layers, epithelial debris and fungal hyphae produce the dry crusts characteristic of the disease. The lesions progress if suitable environmental conditions for mycelial growth exist, including a warm humid atmosphere, and a slightly alkaline pH of the skin. Dermatophytes are all strict aerobes and the fungi die out under the crust in the center of most lesions leaving only the periphery active. It is this mode of growth which produces the centrifugal progression and the characteristic ring form of the lesions (hence xe2x80x9cring-wormxe2x80x9d). Secondary bacterial invasion of hair follicles and other tissues is also commonly associated with ringworm infection.
Many common ailments are actually dermatophyte infections. Tinea pedis (athlete""s foot or ringworm of the feet) is associated with Epidermophyton floccusum, various species of Trichophyton and, rarely, species of Microsporum and other fungi. Tinea unguium (ringworm of the nails) is caused by Trichophyton rubrum. Tinea cruris (xe2x80x9cJock itchxe2x80x9d of ringworm of the groin) results from infection with Epidermophyton floccusum and species of Trichophyton. Tinea corporis (ringworm of the body) is caused by various species of Trichophyton and Microsporum, involves the smooth and hairless skin and results in either simple scaling or deep granulomas. Tinea imbricata (scaly ringworm) is a disease of the tropics and is apparently caused by a single fungus, Trichophyton concentricum. Tinea barbae (barber""s itch or ringworm of the beard) is caused by various species of Trichophyton and Microsporum. Tinea capitis (ringworm of the scalp and hair) is most common in children but may affect adults. The causative organisms, various species of Trichophyton and Microsporum, may be acquired by contact with infected animals or children. Microsporum audouini is most commonly involved but Microsporum canis and Microsporum gypsum (gypseum) produce deeper, more severe lesions. Trichophyton tonsurans is also known to produce widespread infections in the scalp.
To date, the ringworm problem has, for the most part, been handled by post-infection treatment because an effective vaccine has not been available. The significance of skin pH in the development of ringworm is widely known. The susceptibility of humans to ringworm is much greater before puberty than afterwards when the skin pH falls from about 6.5 to about 4.0. This change is largely due to excretion of fatty acids in the sebum and these fatty acids are often highly fungistatic. For this reason, various kinds of topically-applied agents have been used to kill the infecting fungus and relieve the condition. Many treatments for ringworm are based upon alteration of skin pH by topically applying various agents (e.g. propionic acid, undecylenic acid). Other ringworm therapies have relied upon other topically applied commercially available products such as Conofite and Captan. Orally-administered agents (e.g., Griseofulvin and Ketoconazole) are also available.
Unfortunately, however post-infection treatment cannot completely prevent in many instances. Once therapy is discontinued, reinfection usually occurs. It would therefore be desirable to provide a vaccine for ringworm to prevent infection before these adverse effects are suffered. One of the objects of the present invention is to provide such a vaccine.
In accordance with the present invention, a ringworm vaccine is disclosed comprising antigen from at least one dermatophyte and a suitable carrier. The xe2x80x9cantigenxe2x80x9d can include a single antigen from a dermatophyte or a plurality of antigens as long as at least one antigen is included which will produce a sufficient immune response to confer resistance to ringworm infection upon the recipient of the vaccine. The antigen can also be from more than one dermatophyte. If a preparation from more than one dermatophyte is made the antigen can include antigens which are common to all species of dermatophytes employed and/or antigens which are only specific to certain species. The antigen can be xe2x80x9cfrom a dermatophytexe2x80x9d in that it has at least one epitope which is immunologically identical to or cross-reactive with an epitope which is found in the structure of a dermatophyte or in the structure of substances produced by the dermatophyte during infection (e., toxins which are produced and/or secreted by the organism during infection).
Suitable carriers for administration of vaccines are well known in the art and can include buffers, gels, microparticles, implantable solids, solvents, other adjuvants or any other means by which the antigen of the vaccine can be introduced into a patient and be made sufficiently available to produce an immune response to the antigen. In the preferred embodiments of the present invention the carrier is a lactose-containing solution of Lactated Ringers Solution (or other isotonic solution), aluminum hydroxide gel and formaldehyde. Formaldehyde is added to the preferred embodiments to serve as an agent that will kill dermatophytes and prevent contamination of non-specific fungus or bacteria. Other such agents can also be employed in formulating antigen preparations and vaccines of the present invention.
A method of producing such a ringworm vaccine is also disclosed. The method comprises making an antigen preparation comprising the dermatophyte antigen described above and combining the antigen preparation with a suitable carrier. The antigen preparation can be prepared by any available means for obtaining antigen in a form which can be added to the carrier. Antigen can be isolated for use in such preparations by any available means, including without limitation homogenization of dermatophytes or portions of dermatophytes, fractionation of dermatophyte preparations, production of dermatophyte antigen by recombinant DNA technology, isolation of dermatophyte secretions and culturing of material from ringworm lesions. In the preferred embodiments of the present invention, the antigen preparation is made from homogenized cultures of appropriate dermatophytes. Preferably, all the dermatophytes in the culture are killed before the culture is homogenized (e.g., by the addition of formaldehyde or other agent which kills dermatophytes). The preferred embodiments also aspirate or filter the homogenized culture before it is added to the carrier. Finally, the antigen preparation is added to the carrier such that antigen is present in a concentration sufficient to produce an immune response and/or confer resistance upon administration of the vaccine to a patient.
Methods of treating a patient are also disclosed employing the vaccine of the present invention and vaccines produced according to the method of the present invention. Treatment can be for the purpose of producing immunity to ringworm infection (e.g., prophylactic treatment) or for the purpose of eradicating existing infection. Such patient can be a mammal of any species which is susceptible to infection by dermatophytes. Methods are also disclosed for treating a pregnant patient with such vaccines such that the progeny of the pregnancy exhibit resistance to ringworm infection at birth.
Samples of various dermatophytes are available from commercial supply houses (e.g., Difco, Gibco) Cultures of Microsporum canis, Microsporum gypsum and Trichophyton mentagrophytes have also been deposited by applicants with ATCC pursuant to the Budapest treaty as accession numbers ATCC 20970, ATCC 20971, and ATCC 20972 respectively. Methods of isolating various dermatophytes are also well known to the art and can be found in the Campbell/Stewart Handbook.
The following examples are illustrative of the present invention in certain preferred embodiments. The scope of the present invention is not, however, limited to these examples and is defined by the terms of the claims appended hereto.